Railroad hopper cars are used to economically transport commodities between distantly spaced geographic locations. Granular commodities, i.e., corn, grain and etc., can be rapidly discharged from the hopper car through gate assemblies mounted in material receiving relation relative to standard discharge openings on a bottom of the hopper car. Each gate assembly typically includes a rigid frame connected to the bottom of the hopper car and defining a discharge opening. A gate is slidably movable on the gate assembly frame for controlling the discharge of commodity through the discharge opening. An operating shaft assembly is also mounted on the frame in operable combination with and for moving the gate between closed and open positions.
A typical operating shaft assembly typically includes an elongated shaft supported at opposite ends for rotation about a fixed axis by operating handles which are sometimes referred to as capstans. Each capstan or operating handle is operably connected in nonrotatable relation relative to each end of the operating shaft and is journalled for rotation by an extension on the gate assembly frame. Each capstan has an axially elongated configuration which is unitary or of one-piece construction and often has a generally hollow end exposed to the side of the railcar.
That is, a free end of a conventional capstan is configured to allow an elongated opening bar to be passed through aligned slots on opposed sides of an elongated axis, about which the capstan turns, and further includes a generally square socket for accommodating a drive spindle of a mechanical opener. Their size and shape is not conducive to casting a capstan from steel. Accordingly, a typical capstan is made from cast iron. As known, cast iron also has wear and lubricity advantages over a similar steel part.
Once a hopper car reaches an unloading site, the gate is slid open and gravity causes the commodity within the hopper car to readily flow therefrom. As will be appreciated by those skilled in the art, the commodity within the car exerts a relatively large columnar load on an upper surface of a closed gate. Such downward load on the gate has caused and continues to cause a significant problem in manual opening of the gate at the unloading site. Of course, at the unloading site, time is of the essence and any complications involving opening of the discharge gate to unload the commodity presents serious concerns.
Since the time involved with unloading of the hopper car has become a paramount concern, mechanized gate openers are becoming more common. These mechanical openers, however, are much more abusive to the operating handles or capstans than when an elongated bar is used to manually open the gate. With a mechanical opener, a drive spindle is inserted into and engages the marginal edges of the generally square socket on the capstan to transmit opening torque to the operating shaft assembly. The drive spindle on such mechanical drivers usually includes a guide at the free end of the spindle for guiding the drive spindle into the square opening at the free end of the capstan.
Unless the mechanical opener is operated with care, however, the drive spindle is frequently engaged and turning when it is initially inserted into the square opening in the capstan. The high speed turning or rotating movement of the drive spindle relative to the stationary capstan frequently acts to wear against the marginal edges of the square opening in the capstan. Moreover, and because of the relatively large columnar loading placed on the gate by the commodity within the car, the drive spindle of the mechanical opener frequently slips within the square socket opening defined by the capstan, especially at the onset of the gate opening movements. Additionally, the railcar gate assembly is frequently provided with solid stops for limiting fore-and-aft movements of the gate. After the gate reaches either stop, continuing rotation of the drive spindle of the mechanical opener within the now stopped capstan often results in further wear to the square shaped opening in the capstan.
As known, relative movement between the drive spindle of the mechanical opener and the square socket opening defined by the capstan, regardless of the reason, tends to cause the marginal edges of the square socket opening defined by the capstan to rapidly wear and eventually become circular rather than square in shape. Of course, the more wear imparted to the capstan, greater is the loss in the ability to transmit torque to the operating shaft assembly to thus affect timely opening of the gate.
Presently known solutions to a worn opening on the capstan involves either welding a flat plate with a square hole or opening therein to the free end of the capstan or replacement of the entire capstan. Each proposal has serious drawbacks. First, welding a plate with a square hole therein to a cast iron capstan does not usually produce a strong weld. Thus, the plate must be of a low alloy to allow any sort of welding to the cast iron capstan to be successful. Because the plate is of a low alloy, however, the marginal edges of the square hole in the plate become quickly worn by the drive spindle and the above-mentioned torque requirements. Second, welding a low alloy plate to the capstan requires the railcar having the worn capstans to be taken out of rail service. Third, welding a low alloy plate to the worn capstan requires an experienced and skilled welder. Suffice it to say, welding a plate to the worn capstan is time consuming and is not logistically or financially prudent.
Replacing a worn capstan is likewise time consuming since the railcar again needs to removed and taken out from rail service to affect such replacement. After removing the railcar with the worn capstan from service, considerable time is typically spent disconnecting the worn capstan from the operating shaft followed by the reassembly of the new capstan to the operating shaft. As will be readily appreciated, replacing a worn capstan is expensive as comparted to welding a plate to the free end of the capstan. Removing the capstans from the operating shaft frequently results in inadvertent separation of the operable drive connection between the operating shaft and gate. As such, when the capstans are removed from the operating shaft assembly, the timing relationship between the operating shaft assembly and gate movement can also be adversely affected.
Thus, there is a need and continuing desire for a quick and economical solution to the heretofore known problems associated with worn operating handles or capstans on a railcar operating shaft assembly.